The Mobility Management Entity (MME) is a key control-node for a Long Term Evolution (LTE) network. The MME is responsible for idle mode UE (User Equipment) tracking and paging mobility management Entity (MME) procedures including retransmissions. The MME is involved in the bearer activation/deactivation process and for choosing the SGW for a UE at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation. The MME is responsible for authenticating the user (by interacting with the HSS), for generation and allocation of temporary identities to UEs, for checking the authorization of a UE to camp on the service provider's Public Land Mobile Network (PLMN), for enforcing UE roaming restrictions and so on.
The MME is also the termination point in the network for ciphering/integrity protection for Non-Access Stratum (NAS) signaling and assist with security key management. Lawful interception of signaling is also supported by the MME. The MME also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME from the SGSN. The MME also terminates the S6a interface towards the home HSS for roaming UEs.
The process of migrating eNodeBs from one MME to another is done manually. For example, assuming a MME handles 12,000 eNodeBs and it is desired to move half of them to another MME, each of the eNodeBs must be manually reprovisioned to establish sessions with the other MME. This takes time and is error prone. While some tools may exist to help speed up the process, significant manual interaction is still required.